In order to study the law of pavement settlement after backfilling of urban underground utility tunnel, based on a pipe gallery project in the Xiong'an New Area, in this study, the mechanical calculation model of foundation pit backfilling construction in utility tunnel was established by using the intelligent monitoring and numerical simulation calculation method of on-site backfill soil settlement and deformation, followed by analyzing the pavement settlement and the stress and strain of pipe gallery structure under different working conditions. The main conclusions are as follows: 1) The cumulative settlement of backfill soil and the settlement difference between different soil layers increase with the increase of backfill soil thickness. 2) During the step-by-step backfill construction process, the more backfill sections, the smaller the pavement settlement and uneven settlement, and the greater the deformation of the pipe gallery structure. 3) After construction, the pavement settlement will decrease significantly with the increase of compaction degree. The relevant simulation method and research results can provide reference for the scheme design of similar backfill projects in utility tunnel.